1. Field of the Invention
The present invention relates to an optical waveguide member. The present invention also relates to an optical waveguide assembly including an optical waveguide member. The present invention further relates to an optical module including an optical waveguide member.
2. Description of the Related Art
An optical waveguide member is conventionally known, in the field of optical signal transmission technology, as a light propagating element capable of providing additional functions such as an optical switch, an optical coupler, etc. In recent years, so-called polymer optical waveguide prepared from polymer materials has been developed. A conventional polymer optical waveguide comprises a first cladding section of resin material formed by molding the resin material into plate-like shape with a groove provided on the surface, a core section formed by filling the groove on the first cladding section with another resin material, and a second cladding section formed by laminating a resin coating on the surface of the first cladding section so as to cover the core section. As a polymer optical waveguide member permits a plurality of grooves to be easily formed on the surface of the first cladding section by molding, it allows development of a multi-channel structure having two or more core sections. Further, it has various other advantages. For example, a collective lens surface as a light incident/output end face or a reflecting surface for converting the propagating direction of light propagating through the core section can be formed easily at a desired location on the external surface of the first cladding section (see, e.g., Japanese Unexamined Patent Publication (Kokai) No. 2000-69222 (JP-A-2000-69222)).
On the other hand, a photoelectric conversion module (referred to simply as an optical module) for a mutual conversion of an electric signal and an optical signal, which comprises a circuit board with an photoelectric conversion element (referred simply to as an optical element) mounted on one surface thereof (referred to as a mounting surface), and an optical waveguide member provided on the mounting surface of the circuit board for guiding the light participating in a photoelectric converting action (i.e., a light emitting action or a light receiving action) in the direction parallel to the mounting surface, has been conventionally known (see, e.g., Japanese Unexamined Patent Publication (Kokai) No. 2005-115346 (JP-A-2005-115346)). The optical module of this type can use the optical waveguide member for propagating light acting upon (i.e., emitted or received by) the optical element mounted on the circuit board in a direction perpendicular to the mounting surface, in a direction parallel to the mounting surface, and can form a detachable optical connection to, for example, an optical connector attached to an external optical cable. Therefore, it has the advantage that dimension of a module case in height direction (i.e., a direction perpendicular to the mounting surface of the circuit board) can be effectively reduced. Also, in the optical module of this type, it is relatively easy to establish a multi-channel photoelectric conversion system using the above-described polymer optical waveguide member.
In the above-described polymer optical waveguide member, the dimension of the first cladding section increases in the direction along the surface forming the core section as the number of the core sections (i.e., the number of channels) increases, so that it is difficult to fabricate a multi-channel optical waveguide member having more than 10 channels, under the predetermined dimensional constraint. In this respect, as the configuration described in JP-A-2000-69222 relates only to one dimensional image sensor, an increase in the dimensions of the cladding section due to the increase of the number of channels is acceptable. However, in the optical module used in the general optical transmission system as described in JP-A-2005-115346, it is required to increase the number of channels so as to exceed ten while restraining a dimensional increase of the optical waveguide member.